This book is intended to provide a treatment of the production, properties and applications of X-rays suitable for undergraduate courses in physics. It is hoped that parts of it, at least, will be useful to students on other courses in physics, materials science, metallurgy, chemistry, engineering, etc. at various levels. It is also hoped that parts of it will serve as an introduction to the subject of X-ray crystallography, and to this end the treatment of X-ray diffraction has been designed to show the relation between the simple approach and the more sophisticated treatments. During many years of teaching this subject to Degree, Diploma in Technology and Higher National Certificate students, I have been unable to find a single book which attempts to cover the whole of this field. This lack of a treatment of X-rays and their applications in one volume has prompted me to attempt to fill the gap and this present volume is the result. Obviously in writing such a book I have referred to many existing books and I acknowledge my indebtedness to the authors of all the books which I have used. I believe that all these books are included in the re- ferences at the ends of the chapters but if I have omitted any, then my apologies are offered to the authors concerned.